Windows 8 install error

I am trying to upgrade my computer to windows 8 from windows 7. It has intel i5, 6gig ram, and 1 terabite HD. Every time i try and upgrade, it runs through the whole process, and then says windows 8 could not be installed at this time. Any idea what could be causing this?

Try redownloading from the email link.

If you need to download Windows, write down your new product key and enter it here.

Click to expand...

Than make the ISO, & burn to DVD.

Try a clean install.
http://www.eightforums.com/tutorials/2299-clean-install-windows-8-a.html